Honestly, sometimes I get really fed up of my subconscious - it's like it's got a mind of its own. For example, take my memory (or rather lack of it). I'm sure a psychologist would see something highly significant in how absent-minded I am. I mean I'd forget my head if it wasn't attached to my neck by muscles, ligaments and my oesophagus. There is a television producer and actor called Jimmy Mulville, part owner of the successful Hat Trick Productions, who went to the same secondary school in Liverpool as me. We were having a chat one day and he said to me, "Remember when we used to have science in the new wing in Room 205 with Mr Twoomey who filled in for Mr Abrahmson and he used to give us those bendy metal things with a sort of ... ." I said: "Jimmy, let me stop you there. I can't even remember where our school was, or what it looked like, or what it was called - never mind who taught us!"

Once somebody showed me a group photo of a class I was in. I gazed at it for a few minutes, then I spied a familiar face, "Oh yeah," I said, "there's my best friend, good old Gillespie." Then I looked at another kid and thought, "Why there's good old Gillespie as well and behind him! Well, I do declare - there's my mucker Gillespie." After a while it dawned on me that I thought everybody in our class was called Gillespie and I had no idea what their real names were.

My total inability to recall any of my past leaves me in awe of people whose autobiographies go: "I remember it was a cool spring day. I was in my pram and mother was buying a copy of Descartes' Discourse on Method from Mr Molestrupp, the bookseller, who was wearing a paisley cravat and corduroy trousers. His marmalade cat, Ginger, was sunning himself in the window, looking smart in his new blue flea collar. Strangely, I seem to have forgotten who Mr Molestrupp bought Ginger's collar from."

My autobiography, in contrast, would go something like: "Went to primary school in 1957. On my first day my mum gave me a toy car for being good and then I started writing a column for the Independent."

And even today I still have no memory for the really important stuff. If a doctor or a lawyer says to me: "Mr Sayle, it's terribly, vitally important that you remember to ..." well, I'm gone. They may as well start quacking like a duck because I am never ever going to remember a word of what they say. However, in compensation, I have at least developed a brilliant memory for trivial stuff. I can tell you all about my friend Arabella's worries three years ago about the exact shade of red that she should paint the floor of her kitchen, or I can pass on to you every detail of my friend Siobhan's fake fur frock that looks like spotty dalmation, and where she bought it, and how much it cost. In contrast, last week I read Tolstoy's Anna Karenina, perhaps the greatest psychological novel of the 19th century, but if you were to ask me what it was about, at a stretch I'd say "Russia".

However, my problems with my memory are further complicated by the fact that while I don't have any recollection of things I have actually done, I have very vivid recollections of loads of things that I haven't done. This is because in my other life I am an actor. Now it's a fairly common problem with actors that they become so immersed in the parts they play that they begin to think they are those characters. I suffer from that problem.

For example, a couple of years ago I played an airline pilot in an American television movie and now when I'm a passenger on a flight I will often amble forward to the pilot's cabin and have a chat with him about stall speeds, the new fly-by-wire technology on the Airbus A340 and what a pig the old BAC One-Elevens were to bring into the old west two seven runway at Hong Kong's Kai Tak when there was an easterly blowing in from the South China Sea. "Full flaps, brakes on and no mistake," I'll chuckle before asking in a chummy manner: "Hey, what say, Captain, if I take the stick of this old bus while you get your head down for a bit?"

At this point they usually call the sky marshal, who locks me in the economy toilets for the duration of the flight. Except, that is, on Aeroflot, where they usually let me take the controls so I can bring the old girl into Kiev.